Thin film conductors separated by thin film insulators are the dominant components of thin film circuitry. Electrical shorts in these components may result from roughness in the bottom conductor. The roughness can develop during the depositions of the metal but it increases when the substrate is annealed. Aluminum is a commonly used conductor material for thin film circuits. Pure aluminum films on glass become badly pock marked with spikes after an eight to ten hour anneal at 400.degree. C. The spikes are believed to develop because the large differential expansion coefficient of the aluminum relative to the glass produces very large stresses in the aluminum. The stress is relieved and the energy thereby reduced when the aluminum atoms migrate in the plane of the film to nucleation centers where crystallites grow in the third dimension, out of the plane, viz, spikes.